Allogeneic hematopoietic stem cell transplantation for progressive follicular lymphoma

Immunotherapy following hematopoietic stem cell transplantation: potential for synergistic effects

Hematopoietic stem cell transplantation (HSCT) is a particularly important treatment for hematologic malignancies. Unfortunately, following allogeneic HSCT, graft-versus-host disease, immunosuppression and susceptibility to opportunistic infections remain among the most substantial problems restricting the efficacy and use of this procedure, particularly for cancer. Adoptive immunotherapy and/or manipulation of the graft offer ways to attack residual cancer as well as other transplant-related complications. Recent exciting discoveries have demonstrated that HSCT could be expanded to solid tissue cancers with profound effects on the effectiveness of adoptive immunotherapy. This review will provide a background regarding HSCT, discuss the complications that make it such a complex treatment procedure following up with current immunotherapeutic strategies and discuss emerging approaches in applying immunotherapy in HSCT for cancer.

Current management of follicular lymphomas

After decades of stagnation, the prognosis of patients with follicular lymphomas (FL) has changed substantially within the last few years due to new and effective therapeutic modalities. These include myeloablative therapy followed by autologous stem cell transplantation (ASCT) in younger patients in first remission, which showed a significant prolongation of remission duration in three prospective randomised trials while the impact on overall survival still needs to be determined. Adding the anti-CD 20 antibody Rituximab to conventional chemotherapy resulted in a significant increase in remission rate, remission duration and, in two of four currently available prospective randomised studies, even in a longer overall survival. A prolongation of remission duration was also seen when Rituximab was given as maintenance after cytoreductive therapy including Rituximab. Radio-immunotherapy (RIT) with radioisotopes coupled to monoclonal antibodies produced encouraging data in several phase II studies. New therapeutic perspectives have also emerged from increasing insights into the biology of the disease that unravel molecular targets for novel agents, some of which have entered clinical evaluation already.

Variable incidence of cyclosporine and FK-506 neurotoxicity in hematopoeitic malignancies and marrow conditions after allogeneic bone marrow transplantation

INTRODUCTION

This study examines whether malignant disease under treatment influences the incidence of cyclosporine or FK-506 neurotoxicity after myeloablative conditioning and allogeneic bone marrow transplantation (allo-BMT).

METHODS

Review of 290 patients who received myeloablative conditioning prior to allo-BMT and cyclosporine/FK-506 identified 21 (7.2%) patients with neurotoxicity confirmed by computed tomography or magnetic resonance. Underlying malignancy necessitating allo-BMT included leukemias (67%), lymphoma (10%), myelodysplastic syndrome (10%), and multiple myeloma (MM). Frequency of neurotoxicity by disease was compared.

RESULTS

The highest incidence of neurotoxicity was present with MM (25%), whereas the lowest incidence was present with lymphoma (2.7%). Other diseases demonstrated intermediate incidence, including acute leukemias (10%), myelodysplastic syndrome (6.4%), and chronic myelogenous leukemia (4.9%).

CONCLUSION

Cyclosporine/FK-506 neurotoxicity varied according to the underlying malignancy. The variable susceptibility to the development of neurotoxicity in this population may depend on the interaction of host vasculature with disease specific factors. Understanding the cause of neurotoxicity could improve survival after allo-BMT.

Transplantation strategies for patients with follicular lymphoma

PURPOSE OF REVIEW

This review summarizes the current status and new developments in autologous and allogeneic transplantation strategies for patients with follicular lymphoma including novel concepts of myeloablative radioimmunotherapy, allogeneic transplantation with dose-reduced conditioning, and in-vivo purging strategies using B-cell-specific antibodies.

RECENT FINDINGS

Substantial progress has been made in the clinical management of follicular lymphoma. Besides immunochemotherapeutic approaches combining the B-cell antibody rituximab with conventional chemotherapy regimens, myeloablative chemotherapy or radiochemotherapy supported by autologous peripheral blood stem cell transplantation has been shown to be a highly effective treatment for advanced-stage disease. Dose-reduced conditioning regimens followed by allogeneic transplantation have substantially reduced treatment-related mortality of this approach and ongoing studies are evaluating whether the therapeutic benefit outweighs morbidity and mortality of this potentially curative treatment. Emerging concepts include the use of rituximab for in-vivo purging before reinfusion of autologous stem cells or the application of myeloablative radioimmunotherapy as part of myeloablative consolidation.

SUMMARY

The data on myeloablative therapy followed by autologous stem cell transplantation or allogeneic transplantation are encouraging. Allogeneic transplantation with dose-reduced conditioning should be further evaluated within clinical trials, however, in particular for patients with relapsed or refractory lymphoma. Future prospective randomized clinical trials should reevaluate the role of autologous stem cell transplantation in the era of antibody-based therapy and define the role of radioimmunotherapy and of reduced-intensity allogeneic transplantation.

The role of allogeneic transplantation in non-Hodgkin's lymphoma

The evolution of combination chemotherapy regimens, combined with improvements in supportive care, has incrementally improved survival outcomes for patients with non-Hodgkin's lymphomas (NHL). Although 40-60% of younger patients with diffuse large cell lymphoma can now expect to be cured, significant numbers will either fail to achieve a remission or relapse after attaining a remission. In addition, certain histological subtypes are associated with particularly poor prognoses with combination chemotherapy alone (e.g. mantle cell lymphoma, B-cell prolymphocytic leukaemia). Relatively few of these patients can achieve long-term responses. Other NHL subtypes, whilst associated with more favourable prognoses in terms of overall survival, are rarely, if ever, cured (e.g. most low grade NHL including follicular lymphoma, chronic lymphocytic leukaemia and small lymphocytic lymphoma). For these reasons dose escalation and allogeneic transplantation have been investigated as potential ways of improving outcome, although this has mainly been in the setting of advanced disease. Any possible benefits have frequently been out-weighed by procedural morbidity and mortality. The parallel development of transplantation approaches that limit procedural toxicity along with advances in supportive care require that the role of allogeneic haematopoietic stem cell transplantation in the management of lymphoma be re-evaluated.

Graft-versus-lymphoma effects: clinical review, policy proposals, and immunobiology

The indubitable existence of a graft-versus-lymphoma (GVL) effect is difficult to prove directly. This article reviews the difficulties in interpreting the current literature in this field and, with a number of caveats, argues for the existence of a clinically meaningful GVL effect in follicular, mantle cell, small lymphocytic, and Hodgkin lymphomas. The evidence, however, for a potent GVL effect in diffuse large-cell lymphoma and Burkitt lymphoma is not convincing. Policies for allografting in lymphoma are proposed on the basis of this evidence. The immunobiology of GVL effects is discussed--in particular, the expression of HLA class I and II and co-stimulatory molecules on lymphomas that influence the generation of alloreactive T cells--together with future directions in immunotherapy that may help to eradicate chemoresistant disease.

Stem cell transplantation in follicular lymphoma: progress at last?

Follicular non-Hodgkin's lymphomas usually present in advanced stage and although frequently are chemotherapy-sensitive remain incurable using conventional approaches. Treatment options are evolving rapidly and now include targeted therapies such as monoclonal antibodies. Recent studies, including the EBMTR-sponsored 'CUP Trial' (conventional Chemotherapy, Unpurged autograft, Purged autograft), demonstrate that for patients under age 60 years with recurrent chemotherapy-sensitive disease, autologous stem cell transplantation (ASCT) provides a survival benefit over conventional therapy. Allogeneic stem cell transplantation (alloSCT) has become a more effective option. Although incorporation of TBI into the preparative regimen may increase treatment-related mortality (TRM), relapses appear to be reduced compared to a chemotherapy-alone regimen. Reduced-intensity alloSCT procedures are now being performed at an increasing rate, in part due to a lower risk for TRM. Until more data are available, however, reduced-intensity alloSCT should be considered only in cases where myeloablative conditioning is contra-indicated. There are no clear means for choosing ASCT vs alloSCT, a decision influenced by the amount of residual tumor, disease-responsiveness, degree of marrow involvement and extent of prior chemotherapy. ASCT or alloSCT in first remission remains an investigational procedure. Future considerations include incorporation of novel preparative regimens, in vitro purging techniques, antilymphoma vaccines, post transplant immunotherapy and ex vivo-manipulated donor lymphocyte infusions.

Long-term disease-free survival of patients with advanced follicular lymphoma after allogeneic bone marrow transplantation

Myeloablative allogeneic bone marrow transplantation (BMT) may be curative in patients with follicular non-Hodgkin's lymphoma, however, the impact of this therapy on long-term survival, disease progression and functional status is less clear. Twenty-nine patients (median age 42 years, range: 20-53) with advanced stage follicular lymphoma proceeded to allogeneic BMT a median of 25 (range: 8-154) months postdiagnosis, between 1985 and 2001, and have been followed for a minimum of 2 years. Eleven of 29 (38%) had refractory disease (n = 5 induction failure, n = 6 resistant relapse). Most (27 of 29, 93%) received total body irradiation-based conditioning; stem cell source was marrow from a related donor (n = 20) or unrelated donor (n = 9). Seventeen of 29 patients (59%) were alive a median of 5 years (range: 2-11) post-BMT with a median Karnofsky Performance Score of 100%. Death occurred because of transplant complications in seven patients (cumulative incidence of non-relapse mortality 24%), and progressive lymphoma in five patients (cumulative incidence of refractory/recurrent lymphoma 23%). The 5-year probability of overall and event-free survival was 58% and 53% respectively. Allogeneic BMT has resulted in long-term disease-free survival for approximately 50% of this cohort of patients with advanced follicular lymphoma and most of them now enjoy robust health.

Allogeneic Hematopoietic Stem Cell Transplantation for Lymphoma

For patients with relapsed or refractory Hodgkin's or non-Hodgkin's lymphomas, allogeneic hematopoietic stem cell transplantation (HSCT) is a treatment option when autologous HSCT fails to achieve durable remission or is deemed inappropriate. Allogeneic HSCT can result in long-term survival even in patients with refractory lymphomas. The efficacy of allogeneic HSCT is attributed, at least in part, to an immune-mediated graft-versus-lymphoma (GVL) effect that can also be associated with significant toxicity resulting from graft-versus-host disease. However, clinical evidence of a potent GVL effect is inconsistent. Reduced-intensity conditioning before allogeneic HSCT can facilitate the use of this treatment in older patients and those at high risk. The decrease in toxicity with reduced-intensity regimens may be associated with a loss of antitumor effects. Patients with lymphoma should be selected for allogeneic HSCT on the basis of characteristics that strongly influence transplant outcomes, including histology, chemosensitivity, and donor source.

The role of stem cell transplantation in the treatment of follicular lymphoma

Follicular lymphoma (FL) is highly sensitive to chemo- and radiotherapy. However, cure can not be achieved with conventional chemotherapy. Results from several large clinical trials indicate that 50-60% of patients treated with high dose chemo-/radiotherapy (HDT) and autologous blood stem cell transplantation (SCT) for relapse after standard chemotherapy have a 3-5-year chance of disease-free survival (DFS). Overall as well as disease-free survival are improved in patients with negative results in sensitive PCR assays for the disease-specific t(14;18) translocation in bone marrow (BM) or peripheral blood samples taken after transplantation. These data compare favourably to historical results with standard dose chemotherapy. The role of high dose therapy and autologous stem cell transplantation in the primary treatment of follicular lymphoma is presently addressed in randomized trials. Patients with refractory disease or relapsing from standard as well as high dose therapy can achieve long term complete remissions (CR) with allogeneic blood stem transplantation mainly due to the graft-versus-lymphoma effect of the donor immune system.

Is there a role for reduced-intensity haematopoietic stem cell transplantation for indolent non-Hodgkin's lymphoma?

The therapeutic options for the indolent non-Hodgkin's lymphomas have evolved significantly over the years. However, at present, allogeneic haematopoietic stem cell transplantation (HSCT), despite its significant transplant associated complications, is still the only option which may be delivered with curative potential. The debut of reduced-intensity conditioning regimens has extended the applicability of allogeneic transplants to groups of patients ineligible for conventional myeloablative allografts. However, there are still substantial hurdles to overcome, namely that of relapse, graft-versus-host disease and infection. Whilst follow-up is still relatively limited for a disease group with a median survival of up to 10 years, early results are extremely encouraging and further studies are warranted.